help vs assistance vs aid

Help

-一般性的幫忙, 字義比較闊 (例如幫人完成部份工作, 提供意見/資料, 或者令事情較易完成)
-可以解作「叫救命」
-這個字本身可以解作幫忙的人, e.g. My mother’s help. He was a great help with some of the problems.

Assistance

-提供意見或者資料
-提供經濟上或其他的幫忙 e.g. financial assistance, military assistance
- 身體上的支持 e.g. He could not walk without assistance.
-這個字本身不可以解作幫忙的人。 如果需要的話, 就要將它變做 assistant (助手)

Aid

-經濟上, 設備上的幫忙, 或者以服務形式去幫有需要的人
E.g. Military aid 軍事上的支援, legal aid 法律援助, medical aid醫療的協助, first aid 急救, hearing aid助聽器, computer-aided training 電腦輔助, a visual aid視覺教具, He should be able to read this without the aid of a dictionary.
-這個字本身不可以解作幫忙的人, 但有另一個字可以用, 就是 aide (助手)


3個字當中, 其實各有自已側重的意思

- 當提及到普通的幫忙, help 和 assistance就意思比較相近。
e.g.
I would be of little assistance in the kind of work he was doing.
If you need any help, ask John. He’s always of great help.

- 當提及到專門/ 特別的協助, assistance 和 aid 就意思比較相近
e.g.
Financial assistance, legal aid,
Military assistance or military aid


雖然意思上有時相近, 但始終要視乎慣常的用法 (慣常的配撘)。 否則即使別人明白你的意思, 但都會令人覺得有點兒怪或者不是「地道的英文」。

"Aid" is usually used when it's given out by the government in the form of financial support.
e.g. Government aid was badly needed in many cities and towns after the earthquake.
"Assistance" can be seen as an alternative to the word "aid". In fact, many forms of financial support that the government hands out to the people in need used the word "assistance", e.g. Comprehensive Social Security Assistance（綜合社會保障援助金）, Traffic Accident Victims Assistance（交通意外傷亡援助金）. But you can still use assistance for more general purposes like "thank you for your assistance" in a formal letter.
"Help" is a word for more general use, from day-to-day situations like:
"Don't just stand there! Give me some help!"
To more serious things like:
Hong Kong has offered a lot of help to victims in Sichuan.